The present invention pertains to a tip seal supporting structure for use in a scroll fluid device. The tip seal supporting structure includes a bridge which extends across a portion of a fluid flow port located at an orbit center of one of the involute scroll members of the scroll device and functions to support an end portion of a tip seal carried by the other scroll device during a predetermined portion of the relative orbital motion of the scroll members.
In scroll fluid devices having a pair of meshed axially extending involute spiral wraps defining at least one fluid chamber between them that moves radially between an inlet zone and an outlet zone when one wrap is orbited along a circular path about an orbit center relative to the other wrap, tip seals are widely used in the art to axially seal this fluid chamber. These tip seals are arranged to engage wrap support plates to which the involute spiral wraps are respectively fixedly secured. Whether the scroll fluid device functions as a compressor or an expander, one fluid port typically will be substantially centrally located at the center of one of the involute spiral wraps and extend through the respective support plate. If the tip seals extend substantially the entire length of the involute spiral wraps, as is highly desirable in order to maintain proper sealing of the fluid chamber, the tip seal portion at the inner end of the spiral wrap that does not have the fluid port associated therewith will extend beyond the edge of the fluid passage and will therefore be cantilevered for a predetermined portion of the relative orbital movement of the scrolls. Under these circumstances, the tip seal can vibrate which results in wear and/or destruction of the tip seal.
In order to alleviate this problem, some prior art scroll devices, such as that represented by U.S. Pat. No. 4,824,343, utilize tip seals which do not extend to the innermost end of the involute spiral wrap and therefore will not extend into the centrally located fluid port. Although in these prior known arrangements the tip seal will not be cantilevered during a predetermined portion of the relative orbital movement between the involute spiral wraps, during that portion of the relative orbital movement in which the innermost end of the spiral wrap does not extend into the fluid passage, there is no tip seal to provide for axial sealing at the innermost end of the involute wrap. This can result in some leakage of the fluid, a pressure loss and a decrease in the efficiency of the scroll device.
Therefore, to maximize efficiency, there exists a need in the art for a scroll fluid device which enables the use of tip seals which extend to the innermost end of the involute spiral wraps of the scrolls as much as possible and wherein the tip seal can be axially supported during that portion of the relative orbital movement between the scroll fluid wraps when the innermost end of one of the involute wraps extends beyond the edge of the fluid port.